2
t Test for Independent Means wComparing two samples –e.g., experimental and control group –Scores are independent of each other wFocus on differences betw 2 samples, so comparison distribution is: –Distribution of differences between means

4
Pooled Variance wT observed will use concept of pooled variance to estimate standard error: –Assume the 2 populations have the same variance, but sample variance will differ… – so pool the sample variances to estimate pop variance –Then standard error used in denom of T obs wNote – I’ll show you 2 approaches (you decide which to use based on what data is given to you)

11
(cont.) –Pop up window, “Use Specified Values” and type in the code for Group 1, then Group 2, hit “continue” · For example, can label these groups anything you’d like when entering data. Are they coded 0 and 1? 1 and 2?…etc. Specify it here. –Finally, hit OK –See output example in lab for how to interpret